Gavin Henson and Katya Virshilas dance the tango during the live show of Strictly Come Dancing. Photograph: Guy Levy/BBC/PA

Gavin Henson is hopeful of joining Saracens in the next 24 hours, although the Ospreys were last night considering their legal position after the 28-year-old trained with the Premiership club this week without their knowledge.

The former Wales and Lions centre has not played for 18 months after taking a sabbatical to get over a number of injuries and help look after his two young children. His contract with the Ospreys lasts until the end of this season but his lawyers have argued that it has become void because he has not been paid – at his own insistence – for more than a year.

The Ospreys maintain that the contract is still binding, which would mean Henson could not leave without their consent and a transfer fee and that by talking to Saracens, never mind training with them, he is in breach of it.

Mike Cuddy, the Ospreys managing director, would not comment on whether the region would allow Henson's move to Saracens. When asked yesterday if the Ospreys had consented to Henson training with the Premiership club, he said he was not prepared to speak about the matter until this morning.

Saracens said that signing Henson, who would be a replacement for the injured outside-half Derick Hougaard, was far from a formality.

"The deal is not done," said the club's chief executive, Edward Griffiths. "There are obstacles but we hope to make an announcement by the end of the week. We're in contact with the Ospreys because they hold his registration and have been involved in developing the player.

"We're having discussions with the BBC too. He's on Strictly Come Dancing, which takes a lot of time to prepare for each week. We want Gavin to train during the week and for him to be available for selection on Saturday. But the reality is that he has a commitment to the dance programme and we respect that."

By referring to Henson's registration and the development of Henson by the Ospreys and Swansea, it is clear Saracens share Henson's view about the status of his contract. Under International Rugby Board regulations a team or country who develop a player from a young age are entitled to compensation if he moves countries at the end of a contract.

That is not the same as – and is less expensive than – a transfer fee. Such a payment might not have to be included in the Premiership salary cap.

The Ospreys are furious with Henson, saying that he has reneged on a pledge made in the summer that when he returned to rugby it would be with them.

If the Ospreys contested the legality of Henson's contractual status they would be able to block any move at least until the matter came to court. Under IRB regulations, the Welsh Rugby Union would be "entitled to refuse to give its consent to the issue of a clearance if the player concerned has not fulfilled any of his obligations under the terms of his contract with his club".

The Ospreys and Wales wing Shane Williams said he hoped to see Henson back in action quickly.

"I would prefer it to be with Ospreys because he is such a talent. If it is with Saracens, so be it. I saw him on Strictly the other day and he looked in better nick than ever. I am sure it would only take him a couple of games before he was playing good rugby again."